Steps to Reproduce
Start with some tracks for a single piece of music.
Start a quartz clock, and then start one of them synchronized to the bar.
Say you want to start a second one halfway through the bar. You could figure out what the next beat is, do the math to adjust “StartTime” to start at that beat, and call PlayQuantized with TransportRelative, Beat boundary, and multiplier 1.
But if you’re too close to the beat, then your command won’t clear the queue to the other thread before the beat occurs, in which case it will queue for the next beat, and StartTime will be a beat off.
Desired solution: callback from the audio thread that allows me to adjust StartTime to the actual clock at buffer submission.